Line an 8 x 12 inch casserole dish with tater rounds. Bake 10 minutes at 350 degrees. Layer hamburger and broccoli on tater rounds.
In small bowl mix soup, milk, half of cheese, half of onions and pepper. Pour over hamburger and broccoli. Bake at 350 degrees uncovered for 30 minutes. Sprinkle rest of cheese and onions on top and bake 5 more minutes, or until cheese is melted.